Step 4: Optimize the barrier geometry considering the receptor noise impact, the reductions, the cost and the visual outline of the barrier. As part of this step multiple scenarios of cost vs. improvements charts are generated to visualize the optimization.

The right graphic above shows: Site Map with receiver location Green receiver - meet target noise levels Red receiver - do not meet target noise levels The 2nd optimization restricts the maximum barrier height to 12 ft. The history shows a cost vs. noise reduction breakpoint at iteration step 65. With the barrier height restriction step 65 represents the most cost effective barrier. An extension of the barrier beyond iteration step 65 increase the overall cost of the noise barrier but it does not significantly improve the noise levels in the community.